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    <script>
        // console.log(a, b, c);
        // var a = 1, b = 2, c = 3; // 逗号运算符 也有预解析

        a = (b = 1, c = 2); //
        console.log(a);// 2
        console.log(b);// 1
        console.log(c);// 2
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